“What is the difference between Plasma Membrane and Cytoplasm ?” – if you also have the same question, stay reading this article.
Your every doubt about the difference between plasma membrane and Cytoplasm is going to be clear as we will cover the function of plasma membrane and the function of cytoplasm.
Before discussing more about the function of plasma membrane and cytoplasm, we need to know about the difference between plasma membrane and Cytoplasm.
So, lets get started…
What is the difference between Plasma Membrane and Cytoplasm ?
Although there is a great diversity in the structure of different cells, yet, the basic structural plan is similar in all the cells. It can be expressed as generalized cell.
Each eukaryotic cell is delimited by delicate, thin, elastic but firm selectively permeable plasma membrane or cell membrane. Chemically it is made-up of a bilayer of lipids interspersed with proteins.
The plasma membrane being selectively permeable allows only useful substances to diffuse in and harmful substances to diffuse out. In this way, it regulates the flow of materials into and out of the cell.
Functions of Plasma Membrane
The plasma membrane performs the following functions :
- It provides and maintains the shape of the cell.
- It provides mechanical support for the protection of internal structures of the cell.
- It allows only useful substances to enter into the cells.
- It doesn’t allow harmful substances to enter into the cells.
- It provides specificity to the cells.
Cell Wall ( Outer to Plasma Membrane )
In case of plant cells, outer to plasma membrane is present a non-living and rigid cell wall made-up of cellulose.
The cell wall is freely permeable, allowing the substances in solution to enter or leave the cell. It gives shape and provides rigidity as well as elasticity to bear the stresses and strains.
In between the cell walls of adjoining cells, a gelatinous middle lamella, rich in pectates is present. It helps to hold the cells together.
Functions of cell wall :
- It provides and maintains the shape of a cell.
- It provides rigidity as well as elasticity of the plant cells.
- Plants are able to bear stresses and strains because of the cell wall.
Bulk of the cell is made-up of a dense, viscous, colloidal mass called cytoplasm, present between the plasma membrane and nuclear membrane.
The cytoplasm is a colloidal solution of organic compounds, such as carbohydrates, proteins, lipids, vitamins and a true solution of minerals.
It is the “physical basis” of all the metabolic activities that take place in the cell.
Cytoplasmic Inclusions : In the cell cytoplasm, there are present numerous living and non-living structures, collectively called cytoplasmic inclusions.
(A) The living cytoplasmic inclusions are called cell organelles or protoplasmic inclusions.
(B) The non-living structures are called Deutoplasmic or ergastic bodies.
Organ and Organelle
- Organ is a multicellular structure that performs specific functions.
- Organelle is a part of a cell that performs specific functions.
Cell organelles (the “little organs”)
These are the living cytoplasmic inclusions which are capable of growth and division. They perform specific functions and enjoy the same status in a cell as the organs in the organism.
The various cell organelles found in the cytoplasm of eukaryotic cell are given below :
Endoplasmic reticulum (ER)
Endoplasmic reticulum is an inter-connected network of membrane- lined channels. It is present throughout the cytoplasm of a eukaryotic cell.
It is visible under the electron microscope only. It is connected with the plasma membrane, Golgi bodies and nuclear membrane.
It is of two types viz.
(a) Rough endoplasmic reticulum (RER): It is also called granular endoplasmic reticulum. It is rough in appearance because of the presence of small granular structures named ribosomes on its surface.
It has long, flat, sac-like structures called cisternae.
(b) Smooth endoplasmic reticulum (SER): It is found mostly in the outer part of cytoplasm. It is smooth in appearance with no ribosomes on its surface.
Functions of Endoplasmic Reticulum :
It serves many purposes. Such as:
- It forms cytoskeleton (supporting framework of the cell).
- It provides intracellular transporting system.
- It provides surface for cell secretions and storage.
- It keeps various organelles at their places.
- It helps in the formation of other organelles.
These are small granular structures, without membrane, visible only under the electron microscope. They are usually found attached on the outer surface of endoplasmic reticulum as well as freely in the cytoplasm.
Ribosomes are the smallest known cell organelles. They are the only organelles which are present in all types of cells. Groups of ribosomes are called polysomes.
Functions of ribosomes : They help in the protein synthesis and are known as the “protein factories” of a cell.
Mitochondria (mito-thread, chondrion- granule)
These are popularly known as “power house” of a cell. The mitochondria are seen as thread-like or granule-like structures under light microscope and double walled bag-like structures under electron microscope.
The inner membrane of mitochondrion is produced into several finger-like processes called cristae. The inner membrane is studded with tennis racket-like structures called oxysomes or elementary particles.
The space bounded by the inner membrane is called inner chamber. It is fall of ground substance called matrix. The matrix is rich in enzymes needed in aerobic respiration.
Functions of Mitochondria :
In the mitochondria, respiratory enzymes are present that help in the oxidation of food materials and release of energy.
The energy thus released is stored in the form of energy rich bonds called ATP (Adenosine Triphosphate).
The stored energy facilitates various metabolic activities. Hence, they are called “power house” of a cell.
It is also called Golgi apparatus or Golgi bodies. It is a pile of flattened sacs named cisternae along with small vesicles and tubules present usually near the nucleus.
In case of plant cells, these are called dictyosomes found distributed throughout the cytoplasm.
Functions of Golgi Complex :
The Golgi complex is mainly concerned with the following functions:
- Membrane flow
- Formation of acrosome of sperms.
- Vitellogenesis (process of formation of yolk).
- Formation of lysosomes.
These are small spherical or rounded bodies, bounded by a single unit membrane. Each type of microbody is associated with some specific enzymes.
The most abundant and important microbodies are lysosomes. They are small vesicles scattered in the cytoplasm of animal cells. They contain about 40 different types of enzymes which are hydrolases.
These enzymes help in the digestion of foreign bodies and worn out organelles.
If the enzymes are released into the cytoplasm because of the rupturing of their limiting membrane, these enzymes can digest all the components of the cell. Hence, they are known as “suicide bags of a cell”.
Functions of Microbodies :
The main functions of lysosomes are :
- Intracellular digestion.
- Digestion of foreign bodies.
- Digestion of worn out cell organelles.
- Formation of bones by the digestion of cartilages.
- Metamorphosis (conversion of larva into adult), etc.
The other types of microbodies found in the cells are peroxisomes, glyoxysomes, spherosomes, etc.
It is found in animal cells but absent in plant cells with a very few exceptions. It is present near the nucleus.
It is differentiated into a clear, homogeneous mass of cytoplasm called centrosphere and one or a pair of microtubular centrioles.
Functions of Centrosome :
The centrosome is concerned with the following functions :
- The process of cell division.
- The formation of basal bodies of cilia and flagella.
These are present only in the plant cells and seldom found in the animal cells. These are double walled vesicles of different shapes.
These may be discoidal, ribbon-like, U-shaped, stellate, beaded, oval or spherical. These are capable of division. Depending upon the colour, they are categorized into two types, i.e.,
(i) leucoplasts and (ii) chromoplasts.
(i) Leucoplasts (Leuco-white) : These are colourless plastids as they do not contain any pigment. They help in the storage of food. Depending upon the type of food stored, they are further classified as :
- Amyloplasts : They store carbohydrates,
- Proteinoplasts : They store proteins.
- Eleioplasts: They store fats.
(ii) Chromoplasts (Chrome-coloured) : These are coloured plastids because of the presence of coloured substances called pigments.
They are further grouped into two categories, i.e., (a) photosynthetically inactive, and (b) photosynthetically active.
(a) Photosynthetically inactive plastids : These are found in the petals of flowers and ripe fruits. They provide attractive colours. They contain variously coloured pigments, such as carotene (red- orange), xanthophyll (yellow), etc.
(b) Photosynthetically active plastids : These plastids contain coloured pigments, which are capable of trapping the solar energy and help in photosynthesis.
Depending upon the pigments present and colour of the chromoplasts, they are further divided into three types, i.e., chloroplasts (green coloured), rhodoplasts (red coloured) and pheoplasts (brown coloured).
These are the most abundant photosynthetically active chromoplasts and are green in colour. They contain green coloured pigment named chlorophyll and a small quantity of yellow pigment called xanthophyll.
Life sustains in this universe because of chloroplasts.
They help in the process of photosynthesis during which organic food is produced from CO2 and H2O.
This food becomes the food of the whole of living world, directly or indirectly. These plastids are abundant in the aerial parts of plants, such as leaves, raw fruits like tomatoes, chillies, mangoes, etc.
Rhodoplasts are red coloured and are found in red algae whereas, pheoplasts are brown coloured and are found in brown algae.
Functions of Plastids :
- Leucoplasts help in the storage of food.
- Chloroplasts help in photosynthesis and provide food to the whole of the living world.
- Chloroplasts help to maintain O2 concentration constant.
- Chromoplasts provide attractive colours to the plants and help in attracting pollinating agents.
- They are the best purifiers of air and prevent air pollution.
Deutoplasmic or Ergastic bodies
These are the non-living cytoplasmic inclusions which are not capable of growth or division. These include vacuoles, reserve food, excretory granules, secretory granules and crystals of minerals.
Vacuoles are fluid-filled or solid filled spaces in the cytoplasm. These are covered by the membrane called tonoplast. The fluid present in the vacuoles is called cell sap.
It has several organic and inorganic substances. They include amino acids, proteins, esters, water-soluble pigments, waste materials and minerals dissolved in water.
In Amoeba, Paramecium, etc., the vacuoles contain food and are called food vacuoles. They are a kind of storage sacs.
There are many tiny vacuoles in an animal cell. The cell vacuoles in plants are large and only a few in number. More often, these vacuoles of plant cell get fused to form a large central vacuole.
The cytoplasm is present as a peripheral layer between the plasma membrane and tonoplast. It facilitates rapid exchange of materials between the cytoplasm and adjoining fluids.
In freshwater protozoa e.g. Amoeba, are present contractile vacuoles. They contract and expand, pumping out the excess of water along with the waste materials. This is called osmoregulation.
Functions of Vacuoles :
- The cell sap keeps the cell turgid and maintains osmotic equilibrium of the cell.
- The tonoplast being semipermeable, segregates the waste materials as well as nutrients to be stored in the vacuoles in their concentrated form.
In each eukaryotic cell, usually one but sometimes more than one, usually centric but sometimes eccentric (plant cells), usually spherical but sometimes other shaped, controlling centre called nucleus is present.
The nucleus controls all the metabolic activities, directly or indirectly as well as the formation of various organelles by controlling the synthesis of proteins.
Hence, it is said that “a cell without nucleus is without any future.” The nucleus is bounded by a double membraned, porous, selectively permeable nuclear envelope.
It is filled with a clear jelly like ground substance named nucleoplasm. At least one nucleolus and a network of thread-like structures called chromatin reticulum are found in the nucleoplasm.
The nucleolus is concerned with the formation of ribosomes. The chromatin reticulum condenses into small and thick rod-like structures called chromosomes during cell division.
These chromosomes bear the hereditary units called genes which transmit characteristics from the parents to offsprings. The genes are made-up of complex chemical substance called DNA (deoxyribonucleic acid).
Title : What is the difference between Plasma Membrane and Cytoplasm ?
This article mainly cover that what is the difference between plasma membrane and cytoplasm. These are the following points which are covered briefly in this article.
- Difference between Plasma Membrane and Cytoplasm
- What is Plasma Membrane ?
- Function of Plasma Membrane.
- Cell Wall and its function
- What is Cytoplasm ?
- Cell Organelles
- Deutoplasmic bodies